1. Field of the Invention
The invention is a catalytic method for manufacturing singly or multiply substituted pyridine derivatives from alkynes and nitriles and unsubstituted pyridine from acetylene and hydrogen cyanide.
2. Discussion of Prior Art
The methods for manufacturing pryidine derivatives known up to the present time employ cobalt catalysts in which the metal atom is complexly bonded to pure hydrocarbon ligands of, for example, the allyl or cyclopentadienyl type (DBP 2 416 295, Studiengesellschaft Kohle mbH; corresponding to U.S. Pat. No. 4,006,149 whose disclosure is specifically incorporated herein by reference; DOS 2 615 309, Lonza AG; H. Yamazaki & Y. Wakatsuki, Synthesis, 1976, p. 26). These methods are economically unsatisfactory because of the exhaustion of the catalyst. DBP 2 840 460 specifies a method for the selective manufacture of the polymerization-sensitive 2-vinylpyridine that, subject to certain conditions, allows a much more economical utilization of the same type of catalyst to obtain up to 300 mol of pyridine derivative per gram atom of cobalt. Admittedly, this method can not avoid the employment of large amounts of foreign solvents, which make the product more difficult to process.
A catalytic process that allows the manufacture of unsubstituted pyridine from acetylene and hydrogen cyanide is not known as the present time. Although W. Ramsay was, of course, successful as early as 1876 in obtaining small amounts of pyridine from HCN and acetylene in the gaseous phase at 800.degree. C. in a red-hot iron tube (W. Ramsay, Philos. Mag., 5, 2, 271 [1876]), this uncatalyzed reaction turned out later to be hard to reproduce (R. Meyer & A. Tanzen, Chem. Ber., 46, 3186 [1913]) and is economically impractical.